A nonwoven supported mixed matrix membrane for CH4/N2 separation

Efficiently enriching low-concentration CH4 is pivotal for enhancing the utilization of unconventional energy sources and mitigating greenhouse gas emissions. This study focuses on modifying the overall performance of CH4/N2 separation membranes. A novel mixed matrix membrane (MMM) with a reinforced substrate structure was developed through a straightforward dip-coating technique. This MMM incorporates a polytetrafluoroethylene (PTFE) porous membrane as the supporting framework, while a composite of block polymer (styrene-butadiene-styrene) and metal–organic framework (Ni-MOF-74) forms the selective separation layer. Comprehensive characterization of Ni-MOF-74 and the fabricated membranes was conducted using X-rays diffraction, scanning electron microscope, Brunauer–Emmett–Teller analysis, and gas permeance tests. The findings indicate a robust integration of the PTFE porous support with the membrane layer, enhancing the mechanical stability of the MMM. Under optimal conditions, the mechanical strength of the PM20 membrane (containing 20% Ni-MOF-74) was observed to be 37.7 MPa, representing remarkable increase compared to the non-reinforced MMM. Additionally, the PM20 membrane exhibited an impressive CH4 permeation rate of 92 Barrer (1 Barrer = 3.35×10–16 mol·m·m–2·s–1·Pa–1) alongside a CH4/N2 selectivity of 4.18. These results underscore the MMM's substantial performance and its promising potential in methane enrichment applications.